This invention relates to a stabilizer sleeve fitting adapted to be serially mounted in a drill string to support such string in a borehole and to establish the position of the string in relation to the borehole axis, particularly in the case of deviated or angular drillings.
A drill string comprises a succession of hollow tubular elements having a drilling tool fitted to the lower end thereof. The drilling fluid or mud is pumped down through the string to the drilling tool or cutting bit to lubricate it, and carries the dislodged earth particles back up to the surface through the annular space between the drill string and the wall of the borehole.
To implement the upward flow of the drilling fluid across a conventional stabilizer, its outer wall is typically provided with a series of helical grooves. Such grooves determine, by their width and configuration, the hydrodynamic lift exerted laterally on the stabilizer. With conventional stabilizer constructions, however, it is difficult if not impossible to optimize the design of the outer wall of the stabilizer from the standpoints of both lift and the discharge of the drilling fluid. Such optimization is hampered during the design of the stabilizer due to the existence of the helical grooves, which makes it impossible to accurately calculate the hydrodynamic lift.